POS1451 DISCRIMINATORY CAPACITY OF THE ASAS HEALTH INDEX IN PATIENTS WITH AXIAL SPONDYLOARTHRITIS TREATED IN A TIGHT CONTROL SETTING VERSUS STANDARD OF CARE
Authors: U. Kiltz, A. Moltó, C. López-Medina, M. Dougados, D. Van der Heijde, A. Boonen, F. Van den Bosch, J. Braun
Journal: Annals of the Rheumatic Diseases (2022)

Background Improvement in functioning and health as assessed by the ASAS Health Index (HI) is an important outcome of interventions in patients with axial spondyloarthritis (axSpA). ASAS HI thresholds for measuring improvement have been proposed but not yet tested in an independent intervention trial to study its discriminant capacity. Objectives To test the discriminant capacity of the ASAS HI using data from a randomized, active-controlled trial. Methods In this post-hoc analysis from the tight-controlled, treat-to-target (T2T) trial TICOSPA [1], data of active axSpA patients randomized to either the T2T arm (visits every 4 weeks, prespecified strategy of treatment intensification until achieving low disease activity) or standard of care (SOC; visits every 12 weeks, treatment at the rheumatologist’s discretion) were compared to test whether different thresholds for improvement or achieved state of ASAS HI could discriminate between treatment arms. Week 48 effect sizes (ES) of improvement from baseline were calculated for each treatment arm as Phi Coefficient (higher means better discrimination) and OR (95% CI). Results The table shows the ES between treatment arms for all tested improvements and health states achieved in ASAS HI. Overall, absolute improvement outcomes performed better than percentage changes outcome followed by status outcomes. The absolute improvement of ≥2.0, ≥2.5, and ≥3.0 performed best followed by the 20% improvement. As the ASAS HI ≥3.0 is the smallest detectable change for this outcome, this seem to be the most appropriate proposed outcome. Table 1. Thresholds by treatment groups. Non-responder imputation at 48 weeks Effect size measures TC/T2T UC Phi Coefficient* OR [95% CI] ASAS HI 20% improvement 56.9% 45.8% 0.11 [0-1.0] 0.64 [0.33-1.23] ASAS HI 25% improvement 51.4% 41.7% 0.10 [0-1.0] 0.68 [0.35-1.30] ASAS HI 30% improvement 43.1% 34.7% 0.09 [0-1.0] 0.70 [0.36-1.38] ASAS HI 35% improvement 40.3% 31.9% 0.09 [0-1.0] 0.70 [0.35-1.38] ASAS HI 40% improvement 37.5% 31.9% 0.06 [0-1.0] 0.78 [0.39-1.56] ASAS HI 50% improvement 29.2% 22.2% 0.08 [0-1.0] 0.69 [0.33-1.47] ASAS HI 60% improvement 26.4% 18.1% 0.10 [0-1.0] 0.61 [0.28-1.36] ASAS HI 70% improvement 16.7% 12.5% 0.06 [0-1.0] 0.71 [0.28-1.82] ASAS HI 80% improvement 13.9% 11.1% 0.01 [0-1.0] 0.78 [0.29-2.09] ASAS HI 90% improvement 9.7% 9.7% 0.0[0-1.0] 1.0 [0.33-3.01] ASAS HI improvement ≥1.0 66.7% 61.1% 0.06[0-1.0] 0.79 [0.40-1.55] ASAS HI improvement ≥2.0 55.6% 41.7% 0.14 [0.0-1.0] 0.57 [0.30-1.11] ASAS HI improvement of ≥2.5 44.4% 31.9% 0.13 [0-1.0] 0.59 [0.30-1.16] ASAS HI improvement of ≥3.0 41.7% 29.2% 0.13 [0-1.0] 0.58 [0.29-1.15] ASAS HI improvement of ≥ 3.5 29.2% 22.2% 0.08 [0-1.0] 0.69 [0.33-1.47] ASAS HI improvement ≥4.0 29.2% 22.2% 0.08 [0-1.0] 0.69 [0.33-1.47] ASAS HI improvement ≥5.0 16.7% 12.5% 0.06 [0-1.0] 0.71 [0.28-1.82] ASASHI, end of study, ≤12.0 87.5% 80.6% 0.09 [0.0- 1.0] 0.59 [0.24, 1.47] ASASHI, end of study, ≤5.0 37.5% 33.3% 0.04 [0.0, 1.0] 0.83 [0.42, 1.65] A value of PHI = 0.1 is considered to be a small effect, 0.3 a medium effect, and 0.5 a large effect. Conclusion In this active-controlled trial an absolute improvement in the ASAS HI discriminated best between treatment arms. A similar evaluation is needed in a placebo-controlled trial to be able to propose the best outcome for the ASAS HI in a trial. References [1]Molto A et al. Ann Rheum Dis 2021 Disclosure of Interests Uta Kiltz Speakers bureau: AbbVie, Biocad, Biogen, Chugai, Eli Lilly, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Consultant of: AbbVie, Biocad, Amgen, Chugai, Eli Lilly, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Grant/research support from: AbbVie, Amgen, Biogen, Fresenius, GSK, Hexal, Novartis, Pfizer., Anna Moltó: None declared, Clementina López-Medina: None declared, Maxime Dougados: None declared, Désirée van der Heijde Speakers bureau: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Annelies Boonen Speakers bureau: Abbvie / Galapagos, Consultant of: Galapagos, Grant/research support from: Abbvie, Filip van den Bosch Speakers bureau: Abbvie, Amgen, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB., Consultant of: Abbvie, Amgen, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB., Grant/research support from: Abbvie, Amgen, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB., Juergen Braun Speakers bureau: Abbvie, Amgen, Biogen, BMS, Boehringer, Celltrion, Chugai, Fresenius, Hexal, Janssen, Lilly, Medac, MSD, Mylan, Mundipharma, Novartis, Pfizer und UCB, Consultant of: Abbvie, Amgen, Biogen, BMS, Boehringer, Celltrion, Chugai, Fresenius, Hexal, Janssen, Lilly, Medac, MSD, Mylan, Mundipharma, Novartis, Pfizer und UCB, Grant/research support from: Abbvie, Amgen, Biogen, BMS, Boehringer, Celltrion, Chugai, Fresenius, Hexal, Janssen, Lilly, Medac, MSD, Mylan, Mundipharma, Novartis, Pfizer und UCB